/*
 * Copyright 2017 ~ 2025 the original author or authors. James Wong <jameswong1376@gmail.com>>
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.wl4g.infra.common.crypto.asymmetric.spec;

import static com.wl4g.infra.common.lang.Assert2.notNull;
import static java.util.Objects.isNull;
import static org.apache.commons.lang3.StringUtils.isBlank;

import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.security.KeyFactory;
import java.security.NoSuchAlgorithmException;
import java.security.spec.KeySpec;

import org.apache.commons.codec.binary.Base64;
import org.apache.commons.codec.binary.Hex;

/**
 * Generic asymmetric algorithmic keyPair spec.
 *
 * @author James Wong <jameswong1376@gmail.com>
 * @version v1.0 2019年1月22日
 * @since
 */
abstract class GenericKeyPairSpec extends KeyPairSpec {
    final private static long serialVersionUID = -6748188131949785684L;
    final transient private static Map<String, KeyFactory> keyFactoryCache = new ConcurrentHashMap<>();

    final private String algorithm;
    final private KeySpec keySpec;
    final private KeySpec pubKeySpec;

    // Temporary hex string.
    private transient String keyHexString;
    private transient String pubKeyHexString;

    // Temporary base64 string.
    private transient String keyBase64String;
    private transient String pubKeyBase64String;

    public GenericKeyPairSpec(String algorithm, KeySpec pubKeySpec, KeySpec keySpec) {
        notNull(algorithm, "'algorithm' must not be null");
        notNull(pubKeySpec, "'publicKeySpec' must not be null");
        notNull(keySpec, "'privateKeySpec' must not be null");
        this.algorithm = algorithm;
        this.pubKeySpec = pubKeySpec;
        this.keySpec = keySpec;
    }

    public GenericKeyPairSpec(String keySpecId, String algorithm, KeySpec pubKeySpec, KeySpec keySpec) {
        super(keySpecId);
        notNull(algorithm, "'algorithm' must not be null");
        notNull(pubKeySpec, "'publicKeySpec' must not be null");
        notNull(keySpec, "'privateKeySpec' must not be null");
        this.algorithm = algorithm;
        this.pubKeySpec = pubKeySpec;
        this.keySpec = keySpec;
    }

    public String getAlgorithm() {
        return algorithm;
    }

    @Override
    public KeySpec getKeySpec() {
        return keySpec;
    }

    @Override
    public KeySpec getPubKeySpec() {
        return pubKeySpec;
    }

    @Override
    public String getHexString() {
        if (isBlank(keyHexString) && !isNull(getKeySpec())) {
            try {
                keyHexString = Hex.encodeHexString(getKeyFactory().generatePrivate(getKeySpec()).getEncoded());
            } catch (Exception e) {
                throw new IllegalStateException(e);
            }
        }
        return keyHexString;
    }

    @Override
    public String getPubHexString() {
        if (isBlank(pubKeyHexString) && !isNull(getPubKeySpec())) {
            try {
                pubKeyHexString = Hex.encodeHexString(getKeyFactory().generatePublic(getPubKeySpec()).getEncoded());
            } catch (Exception e) {
                throw new IllegalStateException(e);
            }
        }
        return pubKeyHexString;
    }

    @Override
    public String getBase64String() {
        if (isBlank(keyBase64String) && !isNull(getKeySpec())) {
            try {
                keyBase64String = Base64.encodeBase64String(getKeyFactory().generatePrivate(getKeySpec()).getEncoded());
            } catch (Exception e) {
                throw new IllegalStateException(e);
            }
        }
        return keyBase64String;
    }

    @Override
    public String getPubBase64String() {
        if (isBlank(pubKeyBase64String) && !isNull(getPubKeySpec())) {
            try {
                pubKeyBase64String = Base64.encodeBase64String(getKeyFactory().generatePublic(getPubKeySpec()).getEncoded());
            } catch (Exception e) {
                throw new IllegalStateException(e);
            }
        }
        return pubKeyBase64String;
    }

    private KeyFactory getKeyFactory() {
        KeyFactory kf = keyFactoryCache.get(getAlgorithm());
        if (isNull(kf)) {
            try {
                keyFactoryCache.put(getAlgorithm(), (kf = KeyFactory.getInstance(getAlgorithm())));
            } catch (NoSuchAlgorithmException e) {
                throw new IllegalStateException(e);
            }
        }
        return kf;
    }

    @Override
    public String toString() {
        return "KeySpecPair [algorithm=" + getAlgorithm() + ", pubKeyString=" + getPubHexString() + ", keyString="
                + getHexString() + "]";
    }

}